Snap switch



Feb. 22, 1938. R. H. BENTLEY SNAP SWITCH Filed July 8, 1936 m'mnmmmmnnmHEMWWEIIIIIIIIIHIIIIIII INSULATION INVENTOR ROBERT H. BENTLEY BY HISATTORNEYS Patented Feb. 22, 1938 UNITED STATES- PATENT OFFICE] SNAPswrron Application July 8, 1936, Serial No. 89,642

11 Claims.

Another object of the invention is to improve.

constructions of snap switches of the above type and their operation byreducing thecost of the parts and providing a positive kick-off as theswitch is moved to open circuit position.

Other objects and advantages of the invention will become apparent as itis described in connection with the accompanying drawing.

In the drawing, Figure 1 is a longitudinal section view taken through aswitch embodying the principles of my invention, the section being takenalong the line l| of Figure 2.-

Figure 2 is a plan view of the switch shown in Figure 1 but with thecover 01' the operating mechanism and the snapping mechanism removed.

Figure 3 is a longitudinal sectional view of the switch shown in Figures1 and 2 with the section being taken along line 33 of Figure 2;

Figure 4 is a view similar to Figure 1, the parts being shown in aposition between closed and open-circuit positions.

Figure 5 is a transverse sectional view through the switch shown in theprevious figures with the section being taken along line 5-5 of Figure2. In this view the top cover and operating mechanism have been brokenaway. I

Figure 6 is an exploded perspective view showing the stationary andmovable contacts an switching member and spring strut.

Figure 7 is a detail view, showing in plan, the anchor plate of thespring strut assembly,

Referring to the drawingthe switch mechanism is mounted in an insulatingbase III which is provided with a cavity in its central portion formovement of the switch mechanism. A flat metallic cover l2 fits over:the top of the switch base and has between it and the base a liningofsheet insulation 14. An aperture is provided in the cover directlyover the cavity of the switch base, and a threaded nipple I6 is securedin this aperture by means of which the switch may be secured to anelectric fixture in conventional manner.

The switch is operated by a lever designated generally by the numeral l8comprising two parts l8 and I8", the part l8 being the handle portionprojecting from the nipple i6, and the part l8 being the operatingportion andextending into the cavity in the switch base. The part Illmay be rounded and tapering in a conventional manner while the top I8 isflat and has a rounded end I8 which is adapted to engage in an arcuateseat 20 in a Z-shaped anchor plate designated generally by numeral 20.The operating lever I8 is pivotally mounted upon a transverse pin l9passing diametrically through the nipple It in a conventional fashion..

An over-center spring mechanism provides the means for moving thehereinafter described movable contact 36 with a snap. .This over-centerspring construction comprises a strut designated generally by thenumeral 24 around which is coiled a compression spring 26 which bears atits their lower ends by a transverse-bridge 24. The

legs 24 and 24' are substantially identical with the exception of smalllugs 24, 24 which are struck out laterally in inclined position from thesides of the legs adjacent opposite end edges.

These lugs engage with enlargements 2i) and 20' on the ends of theZ-member 20 and prevent the removal of the Z-member from the strut bymovement longitudinally along the legs 24 and 24'' when once theZ-shaped anchor plate has been mounted upon the strut.

From the bottom ends of the legs 24'- and 24' extend, in oppositedirections, arms 2 and 24 arm 24 being longer than 24 in order toprovide a positive kick-oil as will hereinafter more fully appear. Thecoil spring bears against the top edges of these laterally extending,legs 24, and 24 and agalnsttheunderside of the anchor plate 20 and dueto its compressive strength it presses the anchor plate against the lugs24* and 24, in the absence of pressure being applied to the anchor plateby the operating member l8.

For the purpose of moving the movable contact a U-shaped switchingmember, designated generally by the number 30, is provided. Thisswitching member has supporting trunnions or arms II, 30 extendinglaterally from its parallel leg portions 30 and 20 respectively, inopposite directions and these supporting hearings or arms rest inbearing seats 32, 34 in the top parts of the side walls of the insulatedcasing. A lug 30 projects upwardly between the legs 30 and 30 from thetransverse portion of the switching member and extends into a recess 24*formed in the transverse portion 24 of the spring strut 24, and anotherlug 30 extends downwardly from the transverse portion of the switchingmember in the opposite direction to the lug 30* and in alignmenttherewith. This lug 30 engages with a movable contact, designatedgenerally by the numeral 36, in the manner now to be described.

The movable contact for the switch comprises a cradle-shaped memberstamped from sheet metal and having the form as best illustrated inFigure 6. This cradle comprises parallel side walls 36, 36 which areidentical except for a pair of contact fingers 36 and 36 which extendlengthwise from the sides of the plates 315 and 36 at the bottom edgesthereof, the end portions of these arms being bent or inclined inwardlytoward each other to facilitate the engagement thereof with the fixedcontacts 40 and 42 of-the switch in the manner to be presentlydescribed. The parallel side walls of the cradle are joined atthe'central portions of their bottom edges by a saddle 36 which has acentral recess or bearing 36' into which the lug 30' of the switchingmember extends. Preferably the width of the cradle 36 is approximatelyequal to that of the width of the cavity in the switch base so that theside walls 36 and 36 of the cradle may slide along the interior walls ofthe switch casing and be guided thereby. To guide the movement of thecradle at the bottom, the bottom surface of the saddle 36 slides upontops of parallel ridges 46 and 48 in the bottom of the cavity of theswitch casing, the space between these ridges being left for movement ofthe lug 30 of the switching member. Legs 36, 36 at the opposite end ofthe side plates 36, 36 from the contacts 36 and 36 have their bottomsurfaces in alignment with the bottom surfaces of the contact fingers 36and 36 and these surfaces also assist in the guiding of the movement ofthe cradle as they slide along the channels 50 and 62 in the casing,these channels being parallel to the ribs 46 and 46 and at the outerside ofissuing from the casing through suitable channels or passages.The bottom edges of the con tacts 40 and 42 are slotted providing forthe entrance of the contact fingers 36 and 36, Due to the inclination ofthese contact fingers and the resilient nature of the metal from whichthey are formed these fingers may readily engage with the fixed contactsand firmly press against them to give good electrical contacts. I

In order to provide a positive kick-oil or release of the contactfingers 36 and 36 from the fixed contacts, the arm 24' of the springstrut is of sufficient length and its end surface is curved to engagethe vertical wall Ill of the cavity in the switch casing as theoperating lever is moved from the position shown in Figure 3 to theposition shown in Figure 1. Figure 4 shows the operating lever andswitch parts in an intermediate position with the cam surface of thearms 24 engaging the vertical wall. In the position shown in Figure 4the movable contacts have not yet disengaged the fixedcontacts but theswitching mechanism is approaching dead-center position and any furthermovement toward or through dead-center must inevitably result in apositive pushing of the movable contact away from the fixed contacts byreason of the pushing effect of the strut against the switching member,the parts being carefully dimensioned to accomplish this result.

From the foregoing it will be apparent that as the operating lever i8 ismoved from the position shown in Figure l to the position shown inFigure 2 the spring 36 will be compressed by rea-' son of the downwardmovement of the anchor member 20 under the influence of the lower end ofthe operating member I8. As this spring is compressed and the strut 24and operating lever l8 moved into alignment the mechanism will movethrough dead-center position and cause swinging movement of theswitching member 30 in counter-clockwise direction. This swingingmovement will be imparted to the movable contact cradle 36' by reason ofthe engagement of the lug 30 of the switching member with the saddle 36and the contact cradle and contacts 36 and 36 will thereupon come intoengagement with the stationary contacts 40 and 42.

The principles of this invention may readily be applied to a double poleconstruction. In so doing the central part of the saddle 36 would be ofsheet insulation riveted to the edges of the saddle adjacent the sidewalls 36, 36 Additional contact fingers like 36 and 38 would be providedparallel to and above 36 and 36'. These additional fingers would engageadditional stationary contacts like 40 and 42 which would be placedabove the contacts 40 and 42 and insulated therefrom. The height of thecontacts 40 and 42 could be reduced to accommodate the additionalstationary contacts in the grooves already provided in the casing.

Many modifications within the scope of my and therefore I do not limitmy invention to the specific embodiment of the switch as shown anddescribed in the foregoing specification.

1. In an electric snap switch, an insulating base having a cavitytherein for switch mechanism, a cover, an operating lever extendingthrough said cover and having a portion extending into said cavity, astamped sheet metal contact having a pair of parallel side platesslidable along and guided by, the side walls of said cavity andconnected by a saddle slidable along the bottom of said cavity, a yokehaving a lug entering an aperture in said saddle for imparting movementof said yoke to said movable contact, and over-center spring meansoperated by said lever to move said yoke and movable contact with asnap, and,a pair of stationary contacts engageable by said movablecontact.

2. In an electric snap switch, an insulating base having .a cavitytherein for switch mechanism, a cover, an operating lever mounted onsaid cover and having a portion extending into said cavity; movablecontact means having a pair of parallel side plates slidable along andguided by the side walls of said cavity and: joined by-a invention willoccur tothose skilled in the art saddle, a yoke engaging with saidsaddle and imparting movement of said yoke to said movable contactmeans, over-center spring means operated by said lever to move said yokeand movable contact means with a snap, and a pair of stationary contactsengageable by said movable contact means.

3. In an electric snap switch, an insulating base having a cavitytherein for switch mechanism, a cover, an operating member extendingthrough said cover and having a portion extending into said cavity,movable contact means having a pair of parallel side plates slidablealong and guided by the side walls of said cavity and joined by asaddle, the bottom edges of said side plates sliding along the floor ofsaid cavity as said movable contact means is operated, snappingmechanism to move said contact means with a snap as said operatingmember is operated, and fixed contacts engageable by said movablecontact means.

4. A unitary spring strut assembly for electric snap switches,comprising a strut member stamped from sheet metal into U-shape havingparallel arms, lateral extensions from said arms adjacent their joinedends and lugs struck from said arms adjacenttheir free ends, a springcoiled around said arms and resting on said extensions, an anchor plateurged against said lugs by said spring whereby said strut and spring andplate are held in unitary condition, said anchor plate being of Z-shapeand having its ends pressed into engagement with said strut arms duringassembly to hold said parts in assembled condition:

5. A unitary spring strut assembly for electric snap switches,comprising a strut member stamped from sheet metal into U-shape havingparallel arms, lateral extensions from said arms adjacent their joinedends and lugs struck from said arms adjacent their free ends, a springcoiled around said arms and resting on said extensions, an anchor plateurged against said lugs by said spring whereby said strut and spring andplate are held in unitary condition, the transverse portion of saidU-shaped strut having an aperture for reception of a part of a switchyoke, and said strut arms having recesses communicating with saidaperture for another part of a switch yoke.

6. In an electric snap switch, an insulating base havinga cavity thereinfor switch mechanism, a cover, an operating lever mounted on said coverand having a portion extending into said cavity, movable contact meanshaving a pair of parallel side plates slidable along and guided by theside walls of said cavity and joined by a saddle, a yoke engaging withsaid saddle and imparting the movement of said yoke to said movablecontact, said movable contact means having resilient contact fingers atone edge of said side plates, stationary contacts engageable by saidfingers, and over-center spring means operated by said lever to movesaid yoke and movable contact means with a snap.

'7. In an electric switch, an insulating casing having a cavity thereinfor switch mechanism, a

metal cover plate with an aperture therein, a nipple secured in saidaperture, an operating lever pivotally mounted in said nipple andhavinga handle portion extending out of one endoi the nipple and havingan operating portion extending out the other end of the nipple into saidcavity, a switching yoke-mounted in said casing, a spring strut unitengaged with said operating lever and said yoke for causing said yoke tomo e with a snap motion as said lever is operated, said spring strutunit comprising a strut and a spring surrounding saidstrut and an anchorplate, a movable contact slidable along the bottom of the casing, saidcontact being stamped from sheet metal into U-shape, said contact havingan aperture for receiving a portion of said yoke whereby motion of saidyoke is transmitted to said contact. 7

8. In an electric snap switch, an insulating base having a cavitytherein for switch mechanism, a cover, an operating member extendingthrough said cover and having a portion extending into said cavity,movable contact means having a pair of parallel side plates slidablealong and guided by the side walls of said cavity and joined by a sadde,the floor of said cavity having parallel ribs formed thereon, the bottomedges of said side plates sliding along the floor of said cavity andsaid saddle sliding upon said ribs as said movable contact means isoperated, snapping mechanism to move said contact means with a snap assaid operating member is operated, and fixed contacts engageable by saidmovable contact means.

9. In an electric snap switch, an insulating base having a cavitytherein for switch mechanism, ,a cover, an operating lever extendingthrough said cover and having a portion extending into said cavity,movable contact means having a pair of parallel side plates slidablealong and guided by the side walls of said cavity and joined by a saddleof insulating material, a yoke engaging with said saddle and impartingmovement of said yoke to said movable contact means, over-center springmeans operated by said lever to move said yoke and movable-contact meanswith a snap, and a pair of stationary contacts engageable by saidmovable contact means.

10. In an electric snap switch, an insulating base having a cavitytherein for switch mechanism, a cover, an operating member extendingthrough said cover and having a portion extending into said cavity,movable contact 'means having a pair of parallel side plates slidablealong and guided by the side walls of said cavity and joined by a saddleof insulating material, the bottom edges of said side plates slidingalong the floor of said cavity as said movable contact means isoperated, snapping mechanism to move said contact means with a snap assaid operating member is operated, and fixed contacts engageable by saidmovable contact means.

ll. In an electric snap switch, an insulating base having a cavitytherein for switch mechanism, a cover, an operating lever mounted onsaid cover and having a portion extending into said cavity, movablecontact means having a pair of parallel side plates slidable along andguided by the side walls of said cavity and joined by a

